A database management system (DBMS) can use transaction control in incremental or progressive backups. In a progressive backup, a system can use shadow pages and “copy-on-write” (COW) technologies to manage the backup when multiple processes update a same data item. In a system using COW technologies, when multiple processes update a data item, a private copy of the data item is created for each process that modifies the data item. The modification can occur at the private copy of the data item. The changes made by one process may be invisible to other processes. If a process accesses the data item without modifying the data item, a private copy need not be created. Accordingly, the number of shadow pages created at a given time for a data item can be proportional to the number of processes modifying the data item at the given time.